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A 19-YEAR-OLD man was admitted to the emergency department after a motor vehicle crash. His visual acuity was hand motions OD and 20/20 OS, with moderate periorbital edema and ecchymosis in his right eye. Slitlamp examination disclosed only a mild subconjunctival hemorrhage. The ocular motility was normal, and intraocular pressure was 16 mm Hg OU. Pupillary examination showed a 3+ relative afferent defect in his right eye. Dilated funduscopic examination revealed normal optic nerve with a cup-disc ratio of 0.4 OU. A computed tomographic scan of the head and orbits detected a fracture through the right optic canal. The patient was treated with steroids, and visual acuity improved to 20/400 OD. Retinal nerve fiber layer (RNFL) measurements using scanning laser polarimetry (SLP) (Gdx; Retinal Diagnostic Technologies Inc, San Diego, Calif) were taken at 15 days (Figure 1), 30 days (Figure 2), 45 days (Figure 3), and 90 days (Figure 4) after injury. There was a progressive loss of nerve fibers as shown by the double-hump curve, deviation from normal values, and GDx parameters. This was consistent with optic nerve atrophy revealed by ophthalmoscopy 45 days after injury. During the 90 days of follow-up there was no change of the cup-disc ratio.
Scanning laser polarimetry printout 15 days after injury. The examination results were completely normal.
Scanning laser polarimetry printout 30 days after injury. The "superior/nasal" ratio is the first parameter to become abnormal.
Scanning laser polarimetry printout 45 days after injury. The parameter "the number" is greater than 30, and "ellipse modulation" is outside normal limits.
Scanning laser polarimetry printout 90 days after injury. Diffuse loss of nerve fibers is evident.
Scanning laser polarimetry is a noninvasive method that provides in vivo quantitative assessment of the peripapillary RNFL. This technique measures the change in the state of polarization of an illuminating laser beam known as retardation, which is caused by the birefringence of the RNFL. Retardation is linearly correlated with RNFL thickness in monkey eyes1 and corresponds with known properties of the RNFL in normal and glaucomatous human eyes.2 Measurable changes in the RNFL retardation signal as determined by SLP are evident in this patient, and the first parameters to become abnormal were the "superior-nasal" ratio, followed by "the number" (≥30) and "ellipse modulation." It is interesting that the number and the superior/nasal ratio were also the best parameters for detecting glaucomatous damage according to other authors.3 - 5 Later a greater decrease in the retardation signal, probably related to a more generalized loss of nerve fibers, is evident. As there is a more diffuse loss of nerve fibers, the ratios returned to normal values. It is likely that the global parameters only later became positive owing to the wide range of values in the normal population given by the instrument. To our knowledge, this is the first time that progression of RNFL loss has been shown with SLP after optic nerve trauma.
Reprints: Felipe Andrade Medeiros, MD, Glaucoma Service, Department of Ophthalmology, University of São Paulo, Ave Brig Luis Antonio 3030/905, 01402-000 São Paulo, Brazil (e-mail: fmedeiros@uol.com.br).
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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